Improvement in electric fuses



H, J. SMJVI'H.v ELECTRIC: FUSE.

l y No. 79,268. Patented June 23,-.-1868 @HMWHWMU fz venan UNITED STATES PATENT OEiIcE.

H. JLIUS SMITH, OF BOSTON, MASSACHUSETTS.

IMPROVEMENT IN ELECTRIC FUSES.

Specicatiou forming part of Letters Patent No. '19,268,4 dated J une 23,1868.

To all whom it may concern:

Be it known that I, H. JULIUs SMITH, of Boston, Suifolk county, State of Massachusetts, have invented certain new and useful Improvements in Electrical Fuses or Exploders; and Ido hereby declare the following description and accompanying drawings are sufcient to enable any person skilled in the art or science to which it. most nearly appertains. to make and use my said invention or improvements Without further invention or experimeut.

This invention consists in improvements in the mode of manufacturing electric fuses, by which they are rendered less costly int construction, more certain of operation, and more convenient in use.

These improvements are in details of construction and arrangement, involving no discovery in electrical science, but a novel application and combination of what is known, so as to produce a new effect, or an old effect in a better manner.

The only electric fuse which resembles mine, and the only one that has been much known or used, is the English fuse; but it is liable to s'nch serious objections that it still remains a desideratum to obtain a fuse that shall avoid its defects. The English fuse has two wires separately insulated, and these are not continued into the cap containing the fulminate, but have to be soldered to wires which proceed from that cap. The salt used as a flux in soldering is apt to attract moisture, and the least introduction of moisture breaks the insulation and destroys the operation ofthe fuse. It frequently happens, moreover, that the two wires become crossed and, in tamping, the insulating` material is cut away, and the wires so exposed as to destroy the insulation. From fthe operation of these causes a large percentage of these fuses fail iu practice, and as their cost is high they are not more economical than reliable. The necessity for soldering, ofcourse, renders them inconvenient to use, even if they were subject to no more serious objection.

It has been my aim in these improvements to remedy these defects, which I do by the use of two wires incloscd in the same insulator, and by carrying the ends of the wires thus iuclosed directly into the cap containing the fulminate, thus avoidin g the soldering process,

so inconvenient and so dangerous to the cer- 1 Fuses made'A in this way have proved in practice to .be con-- taiuty of operation of the fuse.

the cap O, containing the fulminate or explcvsive compound l), surrounding the ends o f the Wires A A.

An outer cylinder, F, of wood, is passed over the metallic cap G, and is charged with gunpowder E. The ends of cylinder F are closed with a water-proof cement, and its surface is covered with grease t0 protect it from the action of water. The cap C, I make of copper, it being struck up from a single piece of that metal.

The fuse is fired by passing a current of elec tricity through the wires A A. The interruption of thecurreut, where the Wires are separated in the cap (l, develops heat, which ig nites the fnlminate and explodes the charge. Having thus' fully described my invention, I do not claim any of the parts separately.

I am aware that it is usual for telegraphie purposes to inclose two or more wires in a common coating; and I am aware that-metallic caps have been struck up from a single piece of metal, and that fuses have been tired by electricity. These, therefore, I do not claim; but

What I do claim, and desire to secure by Letters Patent, is-

Au electric fuse in which the end of a single insulating-cord containing twbinsulated wires is introduced directlyl into the cap containing the f ulminate to be tired, in the manner described.

H. J ULIUS SMITH.

Witnesses J. DENNIS, Jr., WM. DENNIS. 

